On the diurnal evolution of continental shallow cumulus clouds

Shallow cumulus clouds are often observed during summertime over large areas at US Southern Great Plains (SGP). The diurnal evolution of these clouds is closely related to surface fluxes and atmospheric boundary layer development. Using 13 years observations by millimeter wavelength cloud radar at ARM central facility and GEOS satellite images, we carefully select and categorize shallow cumulus days into several groups: fair weather shallow cumulus clouds with small, moderate and large cloud thickness and shallow cumulus evolving into deep convective clouds in the late afternoon. By so doing, we construct composite cases to study passive and active fair-weather shallow cumulus and the transition from shallow to deep convection. 13 years data collected by ARM SGP site will be used to study the differences in cloud dynamics, thermodynamics and meteorological conditions favoring different types of shallow cumulus. These composite cases further serve as test beds for large eddy simulations and single column model studies.